Unsaturated Ni─N₃ single-atom catalysts (SACs) have been explored to overcome the conventional Ni─N₄ structural limitations for electrochemical CO₂ reduction reaction (eCO₂RR). However, their inherently low structural stability has significantly hindered practical applications. Herein, we developed dual-nickel atom catalysts (Ni-DACs) to stabilize unsaturated Ni─N₃ atomic sites by constructing N₃Ni─NiN₃ dual-atom structures (Ni₂─N₆ sites) from coal. Theoretical prediction reveals that Ni₂─N₆ sites exhibit lower energy barriers for *COOH intermediate generation relative to Ni─N₄ sites and reduce the *CO desorption barriers compared to Ni₃─N₆ sites, thereby boosting reaction kinetics for CO generation. Aberration-corrected scanning transmission electron microscopy and synchrotron X-ray absorption fine structure spectroscopy validate the atomic dispersion of Ni dual-atom sites. The prepared Ni-DACs sample achieves the highest Faradaic efficiency for CO (FE_CO) generation of 98.6% at −0.8 V vs. reversible hydrogen electrode (RHE) and maintains a high FE_CO over 94% from −0.8 to −1.2 V vs. RHE. It also shows a superior CO production turnover frequency as high as 7885 h⁻¹ even at 1.19 V overpotential, outperforming Ni-SACs (2615 h⁻¹). This study offers a scalable approach for stabilizing unsaturated Ni─N₃ SACs to forge a path for their application in eCO₂RR.

Electrochemical CO₂ reduction using solid oxide electrolysis cells (SOECs) directly converts CO₂ into value-added chemicals, mitigating greenhouse-gas emissions. Nickel (Ni) is the conventionally used fuel-electrode electrocatalyst, yet its intrinsic catalytic behavior is underexplored. This study systematically evaluates Ni alloyed with 5 at% Fe, Co, or Cu for changes in microstructure, electrochemical activity, and carbon coking resistance. Model electrodes fabricated by pulsed laser deposition are analyzed by scanning and transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy, which confirm homogeneous alloy formation and show that additive metals modulate active site density by modulating sintering behavior, thereby tuning the triple-phase-boundary density in the order Ni > Ni–Cu > Ni–Co > Ni–Fe. Electrochemical impedance spectroscopy reveals that the apparent activation energy (E_a) related to surface reaction decreases for all samples, accelerating CO₂ electrolysis, while sensitivity to the CO/CO₂ ratio rises when the alloying element is less prone to CO₂ dissociation. Diffuse reflectance Fourier-transform infrared spectroscopy and density functional theory calculations indicate that Co and Fe facilitate CO₂ dissociation, whereas Cu facilitates fast desorption of product species and enhances turnover activity. Cu alloying markedly suppresses carbon coking, whereas Co exacerbates it. Enhanced performance and durability are validated by impedance and Galvano-static measurements. These findings demonstrate that Ni–Cu alloy electrodes offer a practical route to boost SOEC efficiency and mitigate coking with minimal structural change.

Solid-state batteries utilizing oxide, sulfide, and polymer electrolytes have garnered significant attention due to their robust safety and their applicability in high-energy-density advanced Li-ion batteries. In this study, we present an innovative three-layer-structured solid electrolyte, including the garnet-dominant composite solid electrolyte (GD-CSE) for solid-state batteries. This newly structured composite solid electrolyte (CSE) demonstrates a high ionic conductivity of around 1 mS/cm, substantial potential stability exceeding 5.0 V versus Li⁺/Li, and an exceptionally high Li-ion transference number of about 0.8 at room temperature. Upon evaluating its application in batteries, symmetric Li cells employing the three-layer CSE exhibit remarkable cycle stability lasting over 800 h at 0.1 mA/cm². Furthermore, a solid-state Li-metal battery configuration (LiFePO₄ (LFP)|three-layer-CSE|Li-metal) demonstrates favorable C-rate performance, achieving 63% at 5.0 C compared to 0.1 C capacity, along with an impressive cycle retention of 99% during 200 cycles at 0.5 C. Additionally, we manufacture solid-state Li-metal pouch-type cells measuring 3.4 × 5.0 cm². These pouch-type cells offer a capacity of 4.5 mAh and exhibit secure behavior even under bending and cutting conditions.

Solid electrolytes, developed to address the safety hazards of liquid electrolytes, still face some issues, such as low ionic conductivity, non-flame retardancy, and poor compatibility with electrodes. Herein, an organic ionic liquid lithium salt (named PQ-Li) with good intrinsic conductivity and flame retardancy was synthesized, and a flexible and homogeneous all-solid “polymer in salt” electrolyte, composed of 73.15 wt% PQ–Li and 26.85 wt% poly(ethylene oxide) (PEO), referred to as PQSE, was prepared. This preparation strategy, based on a dual-functional lithium salt, endows PQSE with great electrochemical performance (e.g., an ionic conductivity of 0.11 mS m⁻¹ at 30°C, and an electrochemical stability window of 5.1 V), excellent flame retardancy, and good compatibility with Li electrodes considering the absent short circuits and lithium dendrites. The sound charge/discharge performance of Li|PQSE|LiFePO₄ cells (e.g., a discharge capacity of 150.6 mAh g⁻¹ at 0.1 C, Coulombic efficiency beyond 99%, and repeatable power-supply processes for light-emitting diode bulbs) exactly results from the formation of a stable solid–electrolyte interface film with a favorable bilayer architecture. Through molecular dynamic simulation and two-dimensional correlation Raman technique, a dual-channel Li⁺ conduction mechanism in PQSE under an electric field has been proposed, with the dominant mode relying on the hopping of Li⁺ in ionic aggregates/bridges, and the auxiliary mode relying on the random movement of PEO segments coordinating with Li⁺. The developed PQSE provides a trade-off of safety, electrochemical properties, and processibility of electrolytes and represents a promising avenue in solid-state lithium battery technologies.

Catalytic CO₂ methanation offers a sustainable approach to convert waste CO₂ into high-value methane (CH₄). However, designing highly efficient and stable catalysts that operate under harsh conditions remains a significant challenge. The interaction between the active metal and the support material (MSI) plays a critical role in determining the activity and stability of the catalyst. Here, we report the tailoring of MSI by regioselective anchoring of Ni and Co around the edges of hierarchical porous zeolite 13X (h13X), leveraging crystal defects modulated by amine and silanol groups. Scanning transmission electron microscopy and electron energy loss spectroscopy analysis confirmed the growth of approximately 3-nm thick nanolayers of Ni and Co around the edges of h13X crystals. The XPS and H₂-TPR analysis of the catalysts revealed shifts in binding energies and reduced H₂ consumption, corroborating stronger MSI and electronic interaction between Ni and Co. The optimized catalyst (AF-7.5NiCo/h13X) exhibited a maximum CO₂ conversion of 74.4% with a CH₄ selectivity of 98% at 20 bar and 400°C under a GHSV of 60,000 mL g_cat^-1 h^-1 and an activation energy of 55 kJ mol^-1. More importantly, the catalyst demonstrated stability, with consistent CO₂ conversion performance over a month, showing no discernible decrease. The enhanced and stable performance of the catalyst is attributed to the stronger MSI and the sub-5-nm thin layers of Ni and Co over h13X.

α-Mo₂C has demonstrated excellent potential in the catalytic conversion of CO₂ to CO. However, it tends to be reduced to thermodynamically stable β-Mo₂C under H₂ atmosphere, leading to deactivation during reverse water–gas shift (RWGS) reaction. In addition, α-Mo₂C cannot achieve an equilibrium CO yield below 500°C. This work first found that KI-doped α-Mo₂C can achieve near-equilibrium CO yields beyond 1000 h at 400°C, 4 bar in the RWGS reaction while maintaining the original α-Mo₂C crystal structure. Further research indicates that the doped KI effectively stabilized the oxygen content in α-Mo₂C, which is critical for stable catalytic activity. This modification not only reduces the formation-desorption energy barriers for CO and H₂O, but also markedly suppresses methane side reaction. Moreover, the incorporation of the KI reduces the oxidation state of Mo, thereby enhancing the surface alkalinity. This enhancement leads to an increased CO₂ conversion rate, thereby achieving near-equilibrium CO yields at 400°C, 4 bar.

Sustainable hydrogen production is essential for decarbonizing energy and chemical manufacturing; however, conventional water electrolysis is limited by the high thermodynamic and kinetic demands of the oxygen evolution reaction (OER). Hybrid water electrolysis addresses this challenge by replacing the OER with more favorable organic oxidation reactions (OORs), reducing energy input while valorizing or remediating abundant biomass- and waste-derived feedstocks. This review presents the first unified assessment that integrates techno-economic analysis with mechanistic insight and electrocatalyst design principles to identify the most viable OOR pathways. We evaluate key substrates, including glycerol, 5-hydroxymethylfurfural, urea, methanol, and ethanol, and summarize advances in noble and non-noble metal catalysts enabling selective partial oxidation at reduced voltages. The remaining challenges in catalyst stability, product separation, membrane durability, and system integration are critically examined. Overall, this review provides a comprehensive framework for guiding the development and industrial deployment of hybrid electrolyzers for low-carbon, value-added hydrogen production.

With the widespread application of lithium iron phosphate (LFP) batteries in electric vehicles and energy storage fields, the number of retired LFP has increased sharply. Therefore, the development of efficient and environmentally friendly regeneration methods is crucial for the sustainable utilization of resources and environmental protection. In this review, failure mechanism of LFP through advanced characterization technologies is summarized, and upcycling strategies based on the failure mechanism are highlighted. Then, the advantages and challenges of traditional hydrometallurgy, direct regeneration, and upcycling in the recovery of spent LFP (S-LFP) are explored. Among them, upcycling mainly includes strategies such as structural optimization, phase transformation, and conversion into other functional materials. Moreover, the application of materials obtained by upcycling exhibits broaden aspect, including reusing lithium-ion batteries, sodium-ion batteries, and catalytic materials, which significantly improves the economic value of S-LFP cathode materials. Finally, the upcycling method by combining advanced characterization technologies and machine learning to promote the applications and establish a unified economic and environmental analysis system to provide clear analysis standards for relevant research is emphasized.

Conversion-type electrodes with extended Li⁺ storage and multi-electron transfer capabilities hold great promise for meeting the growing demand for high energy density. However, most of these materials suffer from inherently poor rate performance and limited capacity reversibility, primarily due to the low diffusivity of metal cations and inevitable structural changes during (de)lithiation. Herein, we report the high first-cycle capacity reversibility of FeS₂ under ultrahigh charging rates. The kinetic properties of the charging process are revealed through electrochemical measurements, and the origin of the outstanding rate performance is further investigated using advanced spectroscopic characterizations. In particular, the exceptionally high apparent diffusion coefficient observed in the electrode reflects the excellent mobility of Fe²⁺ cations, which directly accounts for the remarkable rate capability. Further investigation reveals that the S^2– anion framework of the anti-fluorite structure is well preserved during charging, providing stable channels and sites for Fe²⁺ insertion. Moreover, the high-spin state of Fe²⁺ reduces the energy barrier for its migration into the tetrahedral sites formed by S^2– anions, facilitating rapid and stable ion transport. This study elucidates the origin of the kinetic performance from a mechanistic perspective and provides guidance for the development of conversion-type electrodes in high-power energy storage devices.

Understanding the correlation between spin state and electrocatalytic activity of single-atom catalysts (SACs) may help us to address the sulfur redox kinetics problems in lithium–sulfur batteries (LSBs). Herein, systematic experiments were carried out to study the catalytic activities of Ni SACs with different spin states via modulating the pyrrolic N/pyridinic N ratio. Ni SACs with high-spin state show strong catalytic activity toward lithium polysulfides (LPSs), whereas the Ni SACs with low-spin state have strong adsorption capacity for LPSs. Therefore, the preparation of Ni SACs with an intermediate spin state by controlling pyridinic N and pyrrolic N enables an excellent balance between the adsorption and catalytic. Importantly, the introduction of S atoms can enhance the content of pyrrolic N while ensuring a high total content of pyridinic N and pyrrolic N. Consequently, the sulfur cathode based on Ni-N_pd-pr-SC shows a remarkable battery performance with a high initial capacity of 606 mAh g⁻¹ at 4.0 C and a capacity retention of 81.3% after 300 cycles. It is believed that this work provides a profound understanding of optimizing the spin state of Ni SACs for LSBs.

Metal-acetylide frameworks (MAFs) have emerged as efficient catalysts due to their unique d-π orbital hybridization between transition metal ions and sp-hybridized carbons in multi-acetylenic ligands, forming robust metal-bis(acetylide) moieties. Herein, we report the synthesis of a novel nickel(II)-acetylide framework (H₂TFPP-Ni-AF) featuring well-defined ─C≡C─Ni(PBu₃)₂─C≡C─ (where Bu = ─CH₂CH₂CH₂CH₃) catalytic sites, which demonstrates remarkable photocatalytic CO₂-to-CO conversion rate. The catalyst achieves a CO yield of 52.64 mmol g⁻¹, an average production rate of 13.16 mmol h⁻¹ g⁻¹, and 97.9% selectivity over a 4-h reaction, substantially outperforming its metal-free analogue (H₂TFPP-GDY). Mechanistic insights from the combined experimental and theoretical studies reveal that the enhanced performance stems from the synergistic interplay between Ni^II-bis(acetylide) moieties, which facilitate CO₂ adsorption and activation, and fluoroporphyrin units, which enhance light-harvesting and charge-transport capabilities, leading to bandgap narrowing, improved electron-hole charge separation, and reduced energy barrier for *COOH intermediate formation. Additionally, the electron-deficient fluoroporphyrin acts as an electron acceptor, extracting photogenerated electrons from the Ni(PBu₃)₂ moieties and further promoting charge separation during the photocatalytic CO₂ reduction reaction (CO₂RR). This work provides a rational design strategy for optimizing MAF-based photocatalysts toward solar-driven CO₂ conversion.

Starch, a sustainable precursor for hard carbon (HC) in sodium-ion batteries (SIBs), faces challenges of low carbon yield (~10%), foaming, and excessive graphitization during carbonization. Herein, a unique spatial structural self-regulation strategy is proposed to precisely program the microstructure of starch-derived HC with the pre-oxidation method, transforming its helical chains into a robust, three-dimensional cross-linked framework. This strategy regulates microstructure evolution by inducing self-carbonylation of hydroxyl groups, suppressing foaming and graphitization, and controlling pore evolution at the molecular level to form closed-pore-encoded carbon microdomains. The resulting material achieves a carbon yield of 26%, a 2.6-fold improvement, and a high-density closed-pore structure. Resultantly, CS-O-1400 delivers 385 mAh g⁻¹ reversible capacity, 92.36% initial Coulombic efficiency (ICE), and 278 mAh g⁻¹ rate capability at 2 A g⁻¹. Furthermore, in situ Raman and electron paramagnetic resonance (EPR) technologies jointly reveal that HC with short-range graphitic crystallites triggers intercalation-dominated sodium storage while synergistically coordinating adsorption and pore-filling mechanisms, forming a marked contrast to the stepwise reaction sequence observed in long-range graphitic crystallite configurations. This work demonstrates that spatial structural self-regulation engineering is a simple and efficient approach to optimizing the electrochemical performance of HC for SIBs.

Before aqueous Zn²⁺ can intercalate into two-dimensional hosts, highly reactive water forces the ions to migrate as a [Zn(H₂O)₆]²⁺ complex rather than as bare ions. Upon reaching the interface, the instability of interfacial water further impedes ion transport, limits the intrinsic capacity, and further triggers side reactions that shorten cycle life. To decouple Zn²⁺ storage from the deleterious influence of interfacial water, a coordination environment is engineered at the MoS₂ surface by installing a dense layer of pyrophosphate rich in PO₃⁻ groups. The terminal oxygens of PO₃⁻ chelate Zn²⁺ in a low-strain, multi-dentate fashion, creating additional interfacial storage sites while simultaneously displacing coordinated water. The resulting interface stabilizes interfacial water while accelerating desolvation of hydrated Zn²⁺, lowering the intercalation energy barrier. Concurrently, the protons released from PPI stabilize interfacial water by establishing a local acidic microenvironment, which suppresses water decomposition and arrests ZnSO₄(OH)₆·xH₂O nucleation at its origin. This dual-function interfacial design endows the Zinc-ion storage device with high capacity and exceptional structural stability over extended cycling.

The thermal conductivity of graphene materials rapidly decreases with the increase of thickness, seriously hindering its application potential in high heat flow scenarios. Here, a novel strategy for synthesizing expandable-thickness graphene block (GPB) with high thermal conductivity is proposed via multiscale blending and multistage pressure induction (MBP). The reduction of the in-plane thermal conductivity with the increase of thickness of the proposed GPB-MBP is lowered by more than 94% compared to existing graphene materials, and the maximum thickness of GPB-MBP reaches 12.1 mm, which is more than 10 times that of the existing graphene materials. Compared with the thickest existing graphene material of 1.05 mm, the in-plane thermal conductivity and cross-plane thermal conductivity of GPB-MBP are 4.7–7.4 times and 6.2–6.6 times higher, respectively. The maximum thermal diffusion ability of GPB-MBP reaches 6.3 W/K, which is 8–53 times higher than that of existing graphene materials. Furthermore, the proportional relationship between in-plane thermal conductivity and the logarithm of length was discovered on macroscopic graphene materials for the first time. The new strategy for synthesizing expandable-thickness GPB offers a new approach for high-heat-flux thermal management.

Anode-free all-solid-state batteries (AF-ASSBs) offer high energy density and safety but suffer from low Coulombic efficiency (CE) and poor cycle stability due to uneven Li deposition and interfacial contact loss. Here, we present an Mg-gradient polyacrylonitrile nanofiber protective interlayer (PAN@Mg) for AF-ASSBs. The nanoporous PAN structure and the mixed ionic-electronic conductivity of lithiated Mg facilitate Li Coble creep, guiding Li toward low-stress regions. The PAN@Mg layer, with Mg-rich top and Mg-deficient bottom regions, was separated during Li deposition. This unique configuration, supported by the superior elasticity of PAN nanofibers, alleviates stress-induced solid electrolyte (SE) cracking and maintains interfacial integrity. Furthermore, the separation of Li and SE prevents their direct contact, suppressing side reactions and Li dendrite growth. The cell employing SUS-PAN@Mg achieves stable cycling with an average CE of 99.94% and a 46.8% improvement in cycle retention over SUS@Mg after 300 cycles. Moreover, the ultra-thin (~2 µm) PAN@Mg layer can enhance volumetric energy density up to 925 Wh L⁻¹.

The kinetic bottleneck in solar-driven hydrogen evolution lies in the slow proton and electron delivery, which severely limits the efficiency of proton-coupled electron transfer (PCET). To address this, we report a bioinspired dual-channel strategy using a CdIn₂S₄/Ni(OH)₂ (CIS/NOH) heterojunction. An S-scheme charge-transfer pathway is constructed to spatially separate strong reductants and oxidants, directing electrons to NOH for H₂ evolution and holes to CIS for benzyl alcohol oxidation. More critically, an interfacial hydrogen adsorption energy gradient drives directional proton migration from CIS to NOH, enriching protons precisely at the electron-accumulation sites. This synergy of vectorial electron flow and proton migration co-localizes reactants, dramatically accelerating the PCET process. The optimal catalyst achieves remarkable concurrent production of H₂ (17.96 mmol g^–1 h^–1) and benzaldehyde (12.63 mmol g^–1 h^–1). This work provides a novel blueprint for designing artificial photosynthetic systems by simultaneously managing charge and mass transport.